Algorithm And Implementation Of QC-LDPC Code Codingand Decoding In Visible Light Communication

Visible light communication(VLC)technology is a kind of communication technology that transmits information by using high-speed light and dark scintillation signals emitted by fluorescent lamps or light emitting diodes,which are invisible to the naked eye.That is to say,the communication function is realized by LED.However,in the channel transmission of VLC system,different coding and decoding methods will directly affect the performance of communication.In this paper,the channel coding and decoding are studied.In order to eliminate the interference of light source or noise on VLC system and ensure the high security and reliability of VLC system at low bit error rate,Quasi-Cyclic LDPC(QC-LDPC)code is introduced into VLC system.QC-LDPC codes,as a coding method that has been found and used for a long time,have been widely used in DVB-S2,CMMB,Wi-Fi and other communication systems because of their infinite error-correcting ability close to Shannon limit.Firstly,the research background of QC-LDPC codes is analyzed.According to the analysis of the research status at home and abroad,the research object of this paper is determined.Then,based on the VLC system,the VLC channel is modeled and the channel parameters are determined.In this paper,QC-LDPC codes are constructed by parallel structure.Considering the complexity and throughput of coding,a shift register-based coding method is adopted.Based on the analysis of traditional sum-product decoding algorithm,an improved decoding algorithm is proposed on the basis of layered TDMP algorithm,which speeds up the decoding and reduces the number of iterations.The RTL-level design of QC-LDPC decoder and decoder is completed in Verilog language and verified on Altera's FPGA/EP4CE15E22C8.The throughput of QC-LDPC decoder and decoder is evaluated under the conditions of system clock 50 MHz,code length 3920 and code rate 0.92.The encoder and decoder can reach 49.94 Mbps and 54.12 Mbps,respectively,which are about 6% higher than before improvement and can respond well.Used in VLC system.Figure [48] table [5] reference [51]...